Class P buildings (a subset of Class D) are characterized by combustible prefabricated wood structural members. The exterior walls may be wood studs or an open-wood-skeleton post frame with exterior coverings of prefabricated metal panels or sheet siding. Upper floors and roof are supported on wood joists or trusses. Ground floors are typically concrete slabs.
Construction Type V (wood-frame) of the Uniform, Type IV Basic and Type VI Standard Building Code are included in this class, as are ISO Class 1 buildings. This class is also referred to as Unprotected-protected One-hour Construction.